1. Field of the Invention
The present invention relates to a component supply device for supplying electronic components to a component mounting device which operates to place the received components on a desired article, and more particularly to such a component supply device which is capable of supplying the electronic components with improved efficiency.
2. Discussion of the Prior Art
A known component supply device is provided with a plurality of supply units for storing or holding electronic components to be supplied, and at least one supply table on which the supply units are mounted. These supply units on the table(s) are spaced from each other along a single line, such as a straight line or an arcuate line, and the table(s) is/are positioned to move the supply units along this line so as to supply the electronic components one by one to a component mounting device. The component supply device of the above type includes (a) at least one supply table having a plurality of supply units mounted thereon, each supply unit holding a multiplicity of electronic components of one kind and having a supply portion at which the components are picked up by a component mounting device, the supply portions of the units being spaced from each other along a line, (b) guiding means for guiding the supply table or tables along the above-indicated line, such that the supply table or tables is/are movable in a direction parallel to the line, (c) positioning means for feeding and positioning the supply table or tables in the direction parallel to the line, so that the supply portions of the supply units are successively and selectively brought to a supply position at which the electronic components are transferred to the component mounting device. An example of this type of supply device is disclosed in laid-open Publication No. 63-269600 of unexamined Japanese Patent Application. The supply device as disclosed in this publication has two supply tables, and a table guide device serving as the guiding means, which extends over an operation area where the supply tables supply the electronic components to the mounting device, and a first and a second shunting area provided on the opposite sides of the operation area. The table positioning means used in the supply device includes a carrier operatively connected to a feed screw, a drive motor for driving the feed screw, and a device for selectively connecting or disconnecting to or from a selected one of the two supply tables. In this arrangement, the two supply tables are successively or concurrently used for supplying the electronic components. If the component supply device employs two supply tables, as in the disclosed supply device, the electronic components to be supplied are divided into two groups, each group being mounted on the corresponding one of the two supply tables. This arrangement is advantageous when a lot of supply units are necessary for supplying many kinds of or a large number of electronic components, since each one of the supply tables can be relatively small-sized, as compared with where only one supply table is employed. Such small-sized supply tables can be moved at a relatively high speed with an excellent response, by using a drive motor having a relatively small capacity or driving force, permitting the supply device to efficiently supply the components.
As described above, the component supply device as disclosed in the above-identified publication is provided with only one carrier for feeding the two supply tables. In the case where the two supply tables are successively used, and these two supply tables take turns supplying the electronic components, one of the supply tables which has been used is moved by the carrier from the operation area to one of the first and second shunting areas, and the carrier is disengaged from this table, and is moved to the other shunting area for engagement with the other supply table which will be used, so that the latter table is moved to the operation area. In this case, it takes a lot of time for the supply tables to take turns supplying the components, resulting in lowered operating efficiency of the component supply device.
If the component supply device uses three or more supply tables, the size of each supply table can be made further smaller, and the supply device enjoys the effects as described above to a greater extent. In this case, the supply tables are successively moved from a pre-operation area to the operation area for supplying the components, and then moved from the operation area to a post-operation area after the supply of the components. However, the supply device still suffers from the problem of low operating efficiency, if the device uses only one carrier for conveying the supply tables between the above-indicated pre-and post-operation areas through the operation area.